Art of conveying and separating fibrous materials



P.- P. BOWEN Sept. V10, 1929.

ART OF CONVEYING AND SEPARATI NG FIBROUS MATERIALS Filed Dec. 15, 1926 2 Sheets-Sheet .lllllllllll y jrt%mora ATTORNEY Sept. 10, 1929. P. P. BOWEN 1,728,035

ART OF CONVEYING AND SEPARATING FIBROUS MATERIALS Filed Dec. 15, 1926 2 Sheets-Sheet 2 INVENTOR W ATTORNEY Patented Sept. 10, 1929.

UNITED STATESi PERCY r. BOWEN, or BUFFALO, NEW YORK.

' ART OF CONVEYING AND SEPARATING FIBRCYUfa MATERIALS.

Application filed December 15, 1926, Serial No. 154,876.

My invention pertains to the art of conveying and separating fibrous materials, involving both process and apparatus, whereby a pulverulent or comminuted material is conveyed from a reducing mechanism and is subjected to treatment during the period of its conveyance for effecting the separation of the constituents of such material.

The object in view is to automatically convey fibrous material and to separate one grade of material from a different grade of the same material, with the result that a material of different physical properties maybe graded without recourse to a screening or separating operation as a distinctly different step in the treatment of such material.

My invention is useful, more particularly, in the treatment of ground fibrous materials, such as wood, for the production of a pulverulent impalpable product which has been designated or is known in certain trades as wood flour, the same being a fine powdery substance possessing utility in numerous arts as a filler for certain classes of compositions; but while the invention possesses marked utility in the production of such pulverulent material, it is to be understood that my invention is not restricted to the production of such material but may be utilized for the treatment of various substances adapted to be transported by a moving air current and the physical properties of which are susceptible of gradation by air currents of different velocities. i

The improvement, in the art of conveying and separating involves a process utilizing the flow of air adapted to be charged or loaded with the pulverulent material to be separated, whereby such material is conveyed or transported from a grinding mill or from a source of supply, and during such transportation the flowing air is divided into streams or currents of different velocities, one of which functions as a medium for drawing the fine powdery particles of the material through a screening mechanism, whereas the coarser particles of material are caught by and detained at such screening mechanism, and thereupon the divided currents moving at different velocities operate to discharge the graded materials in different separated paths, whereby the, coarser material and the fine powdery material are delivered separately for utilization as may be desired.

Another part of the invention pertains to the apparatus for grading the materials, including a conduit leading from a grinding mechanism, a. plurality of eXhausters or blowers rotatable on a common axis, said blowers or exhausters being of different capacities, one greater than the other, for the generation of air streams or currents of different velocities and which blowers or exhausters cooperate for'inducing the flow of air within said conduit, whereby the comminuted material is adapted to'be conveyedby the energy of the moving air within said conduit, and screening mechanism intermediate said exhausters or blowers against which stops the coarse particles to be subsequently blown out by the current of lesser velocity andthrough which screening mechanism the finer powdery material is drawn by the exhauster or blowergenerating a stream of higher velocity, thus effecting the gradation of the materials concurrently with the trans portation thereof.

Other functions and advantages of the invention will appear from the following description taken in connection with the drawings, wherein- I 4 y Figure 1 is an end view of an apparatus embodying my invention and adapted for practicing my process, the dotted line illustrating the screen. a i 3 I Figure 2is aside elevation of the apparatus, the dotted lines illustrating the plurality ofexhaustersand the screen positioned intermediate said exhausters. t

Figure '3 is a vertical sectionalelevation taken substantially centrally through the apparatus of Figures 1 and 2. i c

F igures and5 are views in side elevation and edge elevation, respectively, of an ex hauster for the generation of anair current of relatively high velocity. V I

Figures 6 and 7 are views in sideelevation and edge elevation,respectively, of a blower for the generation of an air curreIitofrelatively lowvelocity.

The apparatus illustrated herein as one practical mechanism for carrying out my in. vention embodies a casing, A, which is divided interiorly to produce a plurality of compartments, B, C, which, for convenient reference, may be designated as a primary chamber, B, and a secondary chamber, C. The interior division of the casing is effected by a partition, D, composed in part of a wall of imperforate material, such as sheet metal, and in part of a separating screen, E, composed of wire fabric, screen material, or foraminous material of any desired character, the meshes of which screen E are of the size required to separate and grade the materials. The screen E is attached fixedly to the impertorate wall or partition D, and said partition is fixedly, attached to the casing A, on the interior thereef, see Figure 3. Said casing A is provided on oneside with an open- 'ing constituting the intakea to the plurality of eXh'a-usters and blowers, F, G, two being shown, although the number may be increased should occasion require. Again, the casing A is constructed with a plurality of outlets, I), 0, leading from the primary chamber Band th'e secondary chamber 0, see Figure 2, said outlets, 5,0, providing for the exit of the air currents generated by the blowers,

F, G, respectively,'and for the separate discharge from'the apparatus of the materials separated and graded by the conjoint action of the exhausters F, "G, and the screening mechanism, E.

The material to be treated is delivered to a conduit. H, of a desired length and diameter for the-flow of a currentjof air adapted for the transportation of the material from a, grinding mill or other source of supply for the comminuted material. It is desirable to conple one end of said conduit with a reducing or grinding mill, whereas the other end of the "conduit iscoupled to the casing A for communication with the intake, a, thereof;

As herein disclosed, the blowers and exhausters, F, G, are mounted on a single horizontal shaft,'I, by the rotation of which said exhausters are rotatedat the same-speed and within the respective compartments, B, C. Said shaft passesthrough one side wall of the casing, one end terminating in compartment B near to the intake (1, whereas the shaft for a substantial part of its lengthis outside of the casing. Said outside part of the shaft is journal'ed for free rotation ,ina pluralityof bearings, i, mounted on a: stand,,2", of suitable form, and to this shaift is aili xed a drivepulley, i ad predrerthe reception of a drive belt '(no tjsh'ow'n), whereby the'shaft may be driven from a source of power, such as a line shaft; 'i

The exhausters and blowers, F, G, are shown in operative positions in Figures 2 and 3,-'and the preferred form of such exhausters are illustrated in Figures 4 to 7, inclusive.

The blower and eXhauster G for the generation of a high velocity air current is shown in detail in Figures 4: and 5, the same comprising a hub, g, a series of substantially radial blades, 9, and an imperforate member, 9 The blades, 9, are desirably of a form for generating a current of air of a given velocity, and said blades 9 with the member 9 are fixedly attached to the hub in a suitable manner. The member g is a flat plate, usually disk-shaped, positioned at one edge of the series of blades 9, and this imperforate member constitutes a face plate against which the powdered material is adapted to impinge upon the rotation of exhauster G, said face plate g precluding the lodgment of material against the inside of the casing due to the suction created and to centrifugal force by the rotation of exhauster G.

The blower and exhauster F for generating an air current the'veloci-ty of which is less than that generated by blower G, is shown in Figures 6 and 7, as comprising a hub, f, and a series of radial blades, 7, attached to the hub. The blowers, F, G, are of different capacities,for which-purpose blower F is constructed with a less number of blades than blower G, or conversely; blower G has a greater number of blades than blower F, and, moreover, blower F is not provided with a face plate, similar to the face plate 9 of blower G. Blower F may thus be said to be of skeleton formation in order that air from conduit H may be drawn by the rotation of blower G through the skeletonizedblower F and drawn, also, through the screen E, where bythe material in suspension in the air flowing within conduit H is separated and graded concurrently withthe transportation of such material away from the grinding mill, or other source of initial supply for the material to be treated.

The hubs, f, g, of blowers F, G, are fitted on the shaft I at the respective sides of partition D and screen E, for the blowers F, G. to occupy and to operate within the respective compartments B, C, said blower hubs f, g, being attached fixedly to shaft I in a desirable manner.

The screen E is positioned fixedly between the rotary blowers and exhausters F, G, and occupies a coaxial position relatively to said blowers, the diameter of said screenbeing equal substantially to the diameter of each blower. Asshown in Figure 3, the screen has a central shaft opening, through which freely passes the blower shaft I. v i

In operation, theconduit H is arranged to receive the comminuted material from .a grinding mill, orother source, and the shaft I is driven at a selected speed. for rotating simultaneouslythe exhausters and blowers, F, G, the latter acting conjointly to induce the flow of air at a desired velocity and in a required volume within conduit H, whereby said flowing air functions as a conveyor for the comminuted material held in suspension in said air flow. The inflowing material passes with the air through the intake, at, of easing A, and owing to the different capacities of blowers F, G, the flow of air within conduit H is divided into two currents by the action of said blowers F, G, the blower F gen erating one current of low velocity which emerges from the casing through outlet 6, whereas blower G generates a current of higher velocity adapted to emerge from the casing through exit 0. The high capacity blower G draws it supply of air from conduit H through the spaces between the blades of the skeletonized blower F, and such high I velocity stream of air is sufficient to draw the finer particles of material through the meshes of screen I the face plate 9 of blower G, and the air stream generated by such blower G, operating to carry and deliver the fine powdery material through exit 0. The face plate 9 is in the path of the powdery material, the latter impinging said face plate and being thrown out by centrifugal action of blower G, so as to preclude lodgment of such material within compartment C or against the walls thereof. The screen E acts to hold back, and to separate, the coarse material from the fine powdery material, and such coarse material is blown out of compartment B by the centrifugal action of blower F, whereby the coarse material is precluded from lodging against screen E or accumulating within compartment B. I

The coarse material is thus delivered from one compartment by a low velocity air current generated by one blower and exhauster, whereas the finer material is delivered from a separate compartment by a higher velocity air flow, whereby the materials are graded by the conjoint action of the screen and the blowers, and such materials are delivered in separate independentpaths, to be separately accumulated in collectors and packing machines, or otherwise prepared for use. If desired, the coarse material from exit I) may be carried back to the grinders, to be further reduced and reused in the apparatus.

The treatment of material is carried out by this invention in a rapid, economical and more facile manner, and without resorting to the use of numerous sifting reels, rotex sifters. or other vibrating sifting machinery and bolting methods now ordinarily required for the pro duction of the powdery material known as wood flour, the same being produced from finely ground and pulverized wood usually in the condition of saw dust and shavings. To meet the requirements of the trade in this product, the pulverized material is screened and graded to pass through certain mesh screens, and heretofore the production has required sifting reels, rotex sifters, specially designed air separators, and blowers, the operations of screening and concurrently with the pneumatic transmission "tions ,being performed separately, and at successive stages. This invention, however, does away with special machinery, and the operagrading are carried on of the pulverized material, with the result that speed and economy of production are obtained. i I

The screen E, with or without the partition D, is demountable from withinthe casing, to

enable a screen orscreens of different size me'shto be substituted as and when required, saidscreen when in operative position being stationary or fixed intermediate the plurality of blowers or exhausters.

Having thus fully described the invention, what I claim as new and desire to secure by Letters Patent is:

1. In the art ofseparating and grading fibrous materials, in generating air currents of different velocities having a'common path of movement to the point of separation of the materials, screening fine material from'coarse material at a point of divergence of the different velocity currents by the energy of the high velocity current acting to draw the fine material through the screen, and conducting the diffent velocity currents in separate paths for effecting the separate discharge of the graded materials.

2. In the art ofconveying and grading fibrous materials, the process which consists insetting up the flow of air within a conduit and transporting therein'pulverized material mechanically suspended in the flowing air, 1 generating air currents of different velocities'the source of origin of which is derived from the air flowing within said conduit, dividing'the air currents of different velocities and screening at the point of division the material of one grade from the ma terial of a differentgrade by the energy of the high velocity air current, and conducting the currents of different velocities in separate paths independent of each other.

3. In the art of conveying and grading fibrous materials, the process whichconsists in setting up the flow [of air within a conduit and transporting therein pulverized material mechanicallysuspended in the flowing 'air, generating air currents of different velocities the source of origin of which is the flowing air,separatihg by the high velocityair current the material of one terialof a different grade, and discharging the graded materials in separate'paths by the the process which consists grade from the 'maenergy of the currents of different velocities.

4. In an apparatus for grading fibrous materials, a' plurality of blowers and exhausters of different relative capacities, the axes of rotation of said blowers and exhausters being substantially coincident, and-screening mechanism intermediate the respective" blowers and exhausters andin separating and one of said the line of flow of air to the high capacity blower and exhauster. v

5. In an apparatus for separating and grading materials, a plurality of exhausters or different relative capacities,.the axes of r0.- tation of said exhausters being substantially coincident, screening mechanism positioned intermediate said exhausters, and a conduit within which an air flow is set up by the conjoint action of said exhausters.

6. In an apparatus for separating and grading materials, a plurality of exhausters of different relative capacities for the generationof air currents offdifierent velocities,

the axes of rotation of said exhausters being substantially coincident, means connected for the establishment of an air flow by theconzjoint action of said exhausters, means for the discharge of graded materials inseparate paths, and screening mechanism positioned intermediate said exhausters.

7.. In an apparatus for separating and grading materials, a casing provided with separate exits for gradedmaterialsand with separate chambers, a screen fixedly positioned intermediate said chambers, and a plurality of exhausters operable Within said chambers at the respective sidesof the screen, the axes of rotation of said exhausters being substantially coincident, said, exhausters being of different relative capacities for the'generation of air currentsof different relative velocities.

8. In an apparatus for conveying and grading fibrous materials, a casing provided with separate exits for graded materials, a shaft, a screen within said casing, a plurality of exhausters carried by said shaft. and ope-rable at the respective sides of thescreen for the generation of air currents of different velocities, said exhausters having separate exits, and a conduit within which an air flow is: set up by the conjoint actionv of said exhausters.

9. In an apparatus for conveying and grading fibrous materials, acasing, a shaft, a

exhausters carried bysaid shaft, exhausters being of skeleton formation and theother exhauster provided with blades and an imperforate plate,a separate exit for the respective"exhausters,a screenintermediate said exhausters, and a conduit within which an air flow is set up by the conjoint action of said exhausters. c 10. In an apparatus. for conveying and plurality of grading fibrous materlals, a casing having separate exits for the graded materials, a

,screen' therein, a conduit connected with said casing, and a plurality of blowersvin coaxial relation to each other and positioned within the casing at the respective sides of the screen,

said blowers being-0t different relative capac ities and co-operating mutually for setting up the flow of air Within said conduit and opcrating for the generation of'separatie-air currents of difierent velocities, whereby said terials andfor eiiecting the separate discharge from the casing of different grades of said material.

In testimony whereof I have hereto signed my name this 11th day of December, 1926.v

PERCY P. BOWEN. 

